The invention relates generally to containment cases and, more particularly, to containment cases with enhanced impact resistance.
Gas turbine engines are extensively used to propel an aircraft. Typically used turbofan engines include large, ducted fans placed at the front of the engine. The fan serves to produce greater thrust and reduce specific fuel consumption. During the operation of such engines, there is a remote possibility that a foreign body, such as a bird, could impact the fan and cause severe fan damage. That damage could result in part or all of a fan blade becoming detached from the hub and impacting the fan casing. Such a detached fan blade could cause considerable damage to the aircraft powered by the engine if it were not contained by the fan casing. Similar damage could also result if the fan blade suffered failure through fatigue. In order to prevent such damage, various containment systems have been employed. Conventional containment casings are typically solid metal casings having a thickness sufficient to withstand the impact of a fan blade within the plane of the fan. However, blade containment achieved by these methods generally incurs significant additional weight.
Composite materials are being evaluated for use in containment casings and would provide considerable weight benefits. However, composites can be subject to puncture at the interior surface of the containment casing. In particular, composite fan containment cases are susceptible to damage due to sharp object impact. Accordingly, it would be advantageous to provide an improved containment casing with improved impact resistance.
Monolithic ceramic plates are used in the armor industry to provide an effective barrier. However, monolithic plates would not be desirable for aircraft engine applications, due to the possibility of fragmentation, as well as installation maintainability issues. Accordingly, it would be desirable to achieve the impact-resistance benefits of armor plating, while eliminating above-noted problems associated with the use of such plates in aircraft engine applications.